In the middle of the vast Avalon cemetery in Johannesburg's Soweto township, two gravediggers shoveled soil out of an old grave containing remains buried years ago.

They were preparing the grave to be reused as towns across South Africa are fast running out of space to bury the dead, according to AFP.

Population growth, migration to urban areas and an influx of foreigners has put huge pressure on land in urban areas. Adding to the problem is a cultural resistance to the practice of cremation.

Between 45 and 60 graves are reopened each week on average to allow for second burials in Johannesburg, the country's largest city and economic hub.

Authorities warn that if no action is taken to change how the dead are laid to rest, urban areas will run out of room in as little as 50 years.

"Burial space is fast diminishing. This is caused by the fact that Joburg is currently experiencing high migration," said Reggie Moloi, the city's cemeteries and crematoria manager.

Johannesburg is not the only city in South Africa battling the shortage.

The southeastern coastal city of Durban raised the alarm more than a decade ago.

The city had an unusually high death rate in the 1980s, having been particularly hard hit by, among other things, HIV/AIDS, say officials.

'Run out of burial space'

"We noticed that cemeteries then filled up in a shortest period of time and that quite soon ... (we were) going to run out of burial space," Thembinkosi Ngcobo, the head of parks in eThekwini, which includes Durban, told AFP.

People seeking burial space could soon be turned away, he warned.

"We are facing a very serious problem."

"The situation is dire and not readily understood... because to the eye it seems there is sufficient (space)," said Denis Ing, the deputy chairman of the South African Cemeteries Association.

The public did not grasp the scale of the problem, he said.

The crisis has pushed officials to think creatively about how best to dispose of the dead.

While recycling graves has helped ease the situation, cremation still faces significant resistance from African communities, which see it as unnatural and against tradition.

At Roodepoort near Soweto, the Sipamla family buried 87-year-old mother and grandmother Caroline Sipamla in the same grave as her son.

"Graveyards are very full," said Puleng Sipamla as undertakers covered the remains of her mother.

"We thought it would be easier for us to reopen and it's cheaper than digging a new grave."

Sipamla had made her feelings known on the matter, said her granddaughter Zoleka Sipamla, 23.

"She was pretty clear – no cremation."

Reverend Harold Ginya of the Church of the Nazarene encourages his worshippers to reuse graves – but discourages cremation.

"We are promoting this kind of thing. No one will complain that you are on top of me," he said.

Few black Africans are cremated in Durban, with just one a week on average compared to dozens of burials.

During a recent campaign to raise awareness of the crisis, it became clear that some people in the port city were skeptical of shared graves, said Ngcobo.

The increasing land demands of the living could mean that, among other things, grave recycling would become mandatory, officials warn.

The situation could be eased by a controversial constitutional amendment proposed by the government, which would allow the forcible transfer of land to redress the inequalities of apartheid and colonialism.

"We believe that expropriation of land without compensation will assist us in addressing these challenges," the mayor of eThekwini Zandile Gumede said earlier this year.

Until then, desperate times are calling for desperate measures, including the possible boxing and storage of remains older than 30 years in the corner of existing graves.